Extending Your Test Without Extending Your Test

1
Extending Your Test WithoutExtending Your Test
System

• Jay Nemeth-Johannes
• Bill Watry
• Complete Test
• Loveland, Colorado

2
The Test Engineers Nightmare

• Project is Designed and Contract is Signed
• One Switch Short
• Rack is Full
• For the Want of a Switch

3
Dont Panic

• Often, Extra Capabilities Exist in Test Systems
• Dont Polish Off Your Resume Yet.

4
Where To Look

• Auxiliary Connectors
• Hidden Modes
• Switching inside the Instrument
• Use the Computer as an Instrument

5
Tracking Down Elusive Sources

• Cal Outputs
• Aux Outputs
• Computer Resources
• Power

6
Cal Outputs

• Well Defined Connectors
• Signals are Generally Fixed (e.g. 5kHz Square
  Wave, 1V p-p)

7
Aux Outputs

• Generally Variable
• Tied to Primary Instrument Function (e.g. Sweep
  Ramp)
• Often Under documented

8
Use the Computer

• Bus Clocks
• Serial and Parallel Ports are good digital
  sources
• Video Signals from Monitor Aux Connection
• Sound Card

9
Sound Card As An ARB

• Microsoft Provides System Calls To Control Sound
  Card.
• Once Card Configured and Waveform Downloaded,
  Refresh is Handled in Hardware (No Real-Time
  Issue)
• LabVIEW VIs for W/F Generation at
  www.completetest.com

10
Sound Card
11
Sound Card

• Very Flexible Arb
• Output Levels Dependent on Soundcard
• Max Freq Generally About 25kHz

12
Think Outside the Box

• Power From unused Digital Outputs
• Ohmmeter as Current Source
• Use Signals from DUT

13
Measurements

• Is there a Voltmeter Hiding Somewhere?
• Make a Different Measurement
• Is a Limit Test Good Enough?

14
How About a Scope?

• Versatile
• Often Underused in ATE
• Powerful built-in functions
• Waveform Math
• Masks and Limits
• FFT for Freq Domain
• Powerful Triggering

15
Triggering

• Need to Find Signal Before Measuring It
• DAQ with Pattern Triggers are Tough to do in
  Software
• Look at Using Instrument with Rich Triggering
  just for the Trigger Capabilities

16
Switching

• Switching Allows Reuse of Measurements and
  Signals
• Switching Costs are Generally Calculated as
  /Switch
• However, if Switch Exceeds Current Card or Card
  Cage, Incremental Cost is Much Higher

17
Switch Cost Analysis

• 3 Slot Card Cage 1200
• 40 Chan MUX Card 400
• 120 Switches Cost (1200(4003))/120
  20/Switch
• Incremental Cost of Switch 121 is 1600

18
Avoid Switching

• Use a More Convenient Instrument
• Dont Need Best Instrument, Just Good Enough
• Use Non-Obvious Switches (e.g. Front/Rear
  Terminals)
• Dont Always Need a Switch

19
Combine Functionality

• A More Expensive Instrument That Can Eliminate
  Switching May Be Less Expensive Overall
• Voltmeters With Embedded Switching Are Often Cost
  Effective

20
Conclusions

• Dont Panic, The Solution is Usually There
• Be Aggressive in Ferreting Out Hidden
  Capabilities
• Look at Overall System Costs, Instead of
  Individual Instrument Costs
• Look at Non-Traditional Applications
• The Computer is Part of the Test System